drm/buddy: check range allocation matches alignment

Likely not a big deal for real users, but for consistency we should
respect the min_page_size here. Main issue is that bias allocations
turns into normal range allocation if the range and size matches
exactly, and in the next patch we want to add some unit tests for this
part of the api.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Reviewed-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240219121851.25774-5-matthew.auld@intel.com
Signed-off-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/drm_buddy.c

@@ -771,8 +771,12 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
 		return -EINVAL;
 
 	/* Actual range allocation */
-	if (start + size == end)
+	if (start + size == end) {
+		if (!IS_ALIGNED(start | end, min_block_size))
+			return -EINVAL;
+
 		return __drm_buddy_alloc_range(mm, start, size, NULL, blocks);
+	}
 
 	original_size = size;
 	original_min_size = min_block_size;